Peter_s,
Water Furnace Envision series (dual-speed versions) will get you a COP of 5 on closed loop, but they are probably the exception as that is the most efficient one out there I think. Disclosure: just based on my research; never bought one or sold one and no economic link to anyone in the business.
Water Furnace Envision series (dual-speed versions) will get you a COP of 5 on closed loop, but they are probably the exception as that is the most efficient one out there I think. Disclosure: just based on my research; never bought one or sold one and no economic link to anyone in the business.